Caution on Big Sur Contacts corruption

I've had issues with my Contacts app for a number of months, mainly spinning wheels each time I try to edit or add anything to the new or existing card in Contacts. The 10-second delays became too difficult to use the app, and I've search the forums for ideas on how to fix it.

This morning, in one last mad attempt, I tried to really clean things up, using the ideas laid out in this 2016 thread, but none of the multiple backup Contact Archive files have worked, so I'm posting this in case someone else tries these things or sees similar behavior. Here's what I did this morning:

• I'm running a new M1 Mac Mini, 16G, 2T internal, OS 11.1
• My contacts have 3200 cards
• I made 3 separate backup files of the entire database (File: Export: Contacts Archive...) and placed two of them on my desktop and one on a separate flash drive. I verified that they were each around the same size (100M)
• I then went to Sys Pref: Internet Accounts: iCloud: unchecked Contacts. I've long suspected that the issues I've been having were because of iCloud corruption.
• I then logged into iCloud.com and did something I've never done yet in my troubleshooting: I deleted all Contacts in the cloud. Zeroed out Contacts. Again, I've long wondered if the issue wasn't some corruption here, so I wanted to start fresh.
• I then turned off wifi and Internet connection to my Mini, since in the past, even with Contacts unchecked, there still seemed to be Contacts syncing going on.
• I restarted the Mini, then started following Barney-15E's suggestions at the above link, and deleted the 3 files located at ~/Library/Application Support/AddressBook and emptied the trash.
• I then restarted the Mini again, opened up Contacts, and decided to delete all contacts in there, thinking that may be where the corruption lies. I now have Contacts at zero cards (with the single exception of my own card. I empty the trash.
• I restart the Mini once more, start up Contacts, and then go to import the Contacts Archive. Nothing happened. I waited 5 minutes, giving it time. Still nothing. I went to the second Contacts Archive backup, same thing. I load the flash drive backup version, and still nothing. Palms got sweaty at this point.
• I'm still no connected to the Internet (by choice), so now I replug in the Internet cable and turn wifi back on (yeah I know, only need one). I then go back to Sys Pref: Internet Accounts: iCloud: and check back on the Contacts. There shouldn't be any Contact cards on the iCloud, but cards start appearing in Contacts. Ten minutes later, I have around 2/3rds of the total cards I had. I start checking for cards and realize that what I'm missing the last 7 or so years of updated Contacts, and what I'm seeing is some very old set of cards, probably last updated around 2013.

I'm a backup junky, with Time Machine and a Backblaze account, so there's surely a method of digging in there and finding all my contacts. The biggest issue here, though, is how none of the full Contact Archives worked, and they definitely should have.

At this point, if the Contacts app works as it should—no spinning wheels, no lost text or notes, no lengthy delays—I might leave the missing cards out, and just trust that I can get people's contact info from past and new emails (I use Mail exclusively and my 2 email addresses are both Gmail).

Hope this helps someone. I would like to hear if anyone else sees this issue with fresh full Contact archive files. That really shouldn't have happened.